Self-Diffusion of Ge in Amorphous Ge Si Films Studied In Situ by Neutron Reflectometry.

Ge Si alloys are gaining renewed interest for many applications in electronics and optics, especially for miniaturized devices showing quantum size effects. Point defects and atomic diffusion play a crucial role in miniaturized and metastable systems. In the present work, Ge self-diffusion in sputter deposited amorphous Ge Si alloys is studied in situ as a function of Ge content = 0.13, 0.43, 0.8, and 1.0 by neutron reflectometry. The determined Ge self-diffusivities obey the Arrhenius law in the investigated temperature ranges. The higher the Ge content , the higher the Ge self-diffusivity at the same temperature. The activation enthalpy decreases with from 4.4 eV for self-diffusion in pure silicon films to about 2 eV self-diffusion in GeSi and Ge. The decrease of the activation enthalpy for amorphous Ge Si is similar to the case of crystalline Ge Si . Possible explanations are discussed.